How does MCB operate without relay..?

Answer Posted / maddy

I am studying the bimetallic strip used in MCB.
I am trying to theoretically calculate the temperature rise
of the strip when 1.13In (safe value of current for which
the MCB shouldnot trip) is passed through the bimetallic
strip. I am having the dimensions, resistivity, modulus of
elasticity, flexivity, density of the strip.
I even have the practical values with me for ever few
secons of current passed.
I tried to use the relation MC(dT)=I^2Rt
that is all the heat generated is used in the temperature
rise.
But practically other things need to be considered like
heat loss with environment, also the above formula holds
good for only few seconds and here the resistivity I have
taken constant will also vary.
Please help me out with a relevant solution.

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